High-speed signals that are transmitted through a medium such as a cable or line on a printed-circuit board (PCB) are attenuated and distorted by the medium. Variable delay and high-frequency components add to the distortion. Signal pulses may be spread out and interfere with other pulses. The length of the medium is limited by such attenuation and distortion.
Signal repeaters can be added in the middle of the medium to increase the distance that signals can be transmitted. FIG. 1 shows a signal repeater that can be inserted into a medium. Equalizer 10 receives inputs from one segment of the medium. Equalizer 10 recovers the signal from the input medium, and drives a recovered signal to limiting amplifier 12. The signal is amplified and limited in voltage or signal swings by limiting amplifier 12. Transmitter 14 receives the amplified signal and drives another segment of the medium. Transmitter 14 may use de-emphasis to better drive the signal. For one-tap de-emphasis, the first bit after a transaction may have an increased signal amplitude compared to other bits. The distorted and attenuated signal received by equalizer 10 is recovered, amplified, and driven onto the next segment of the medium by this repeater.
What is desired is a limiting amplifier that has a high gain and a wide band is desirable. A limiting amplifier that can be used in a signal repeater is desirable.